1. Technical Field
The present invention relates to a numerical control machine including a vibration suppressing unit that fluctuates, in a predetermined fluctuation cycle, a commanded rotational speed of a main spindle based on pre-stored main spindle fluctuation data including the fluctuation cycle, and also fluctuates a feed rate of a feed axis while maintaining a constant ratio between the feed rate of the feed axis and the rotational speed of the main spindle.
2. Related Art
As a method for suppressing chattering vibrations in cutting processing, a method disclosed in JP 49-105277 A is known. This method suppresses chattering vibrations by fluctuating the rotational speed of a main spindle during cutting processing with a preset fluctuation amplitude and fluctuation cycle.
Another method for suppressing chattering vibrations is disclosed in JP 11-129144 A in which when chattering vibrations occur, the rotational speed of a main spindle and feed rate of a feed axis are fluctuated while maintaining a constant ratio between the rotational speed of the main spindle and the feed rate of the feed axis. Furthermore, JP 2005-144580A discloses a method in which acceleration/deceleration pattern of rotational speed of the main spindle is preset and it is possible to fluctuate the rotational speed of the main spindle based on the preset acceleration/deceleration pattern while also fluctuating the feed rate of feed axis.
In cutting processing, non-uniform cutting surfaces are caused unless the cutting feeding amount per one rotation of a main spindle is kept constant. In the methods disclosed in JP 11-129144 A and JP 2005-144580 A, because it is possible to keep the cutting feeding amount per one rotation of the main spindle constant, it is possible to suppress chattering vibrations while achieving uniform cutting surfaces.
On the other hand, in the method disclosed in JP 49-105277 A, the rotational speed of a main spindle alone is fluctuated. However, a method for obtaining an actual speed of a main spindle from a sensor mounted with the main spindle and determining a feed rate of a feed axis based on the actual speed so as to maintain a constant cutting feed amount is well-known. Therefore, by combining this method, it becomes possible to suppress chattering vibrations while achieving uniform cutting surfaces in the same manner as JP 11-129144 A and JP 2005-144580 A, JP 49-105277 A.